A. Kiselev BNL, 06/20/2013

A. Kiselev

BNL, 06/20/2013

EicRoot status report and

calorimeter code development

06/20/2013 A.Kiselev

Contents

Overall status

Update on track resolution studies Calorimeter code development &

studies

SVN repository Interface to EIC smearing generator Tracking detector “designer” tools


EIC in FairRoot framework

ROOT VMC VGM “Boost” library …

FairRoot externalpackage bundle

FairBaseC++ classes

CbmRoot

R3BRoot

PandaRoot

eic-smear

EicRoot

-> Make best use of FairRoot development -> Utilize efficiently existing codes developed by EIC

taskforce

FairRoot is officially maintained by GSI; dedicated developers

O(10) active experiments; O(100) users

…

Interface to GEANT

Magnetic fields Parameter

database MC stack handling …

Overall status


EicRoot availability & usage

-> MC points

simulation

SVN -> http://svn.racf.bnl.gov/svn/eic/eicroot eic000* cluster -> /eic/data/FairRoot

digitization “PID” Passreconstruction-> Hits -> “Short”

tracks-> Clusters

-> “Combined” tracks

-> Vertices @ IP

ROOT files for analysis available after each step C++ class structure is (well?) defined at each I/O

stage

End user point of view:

README & installation hints Few basic usage examples

http://svn.racf.bnl.gov/svn/eic/eicroot


Interface to eic-smear EicRoot input

EicRoot output

directly uses eic-smear library calls to import ASCII event files after MC generators …

… as well as “unified” ROOT format event files

is available in eic-smear format with charged particle momentum variables “smeared” by Kalman Filter fit after track reconstruction …

… while other variables modified by smearing generator according to its recipes


Detector view (June’2013)

EMC and tracking detectors ~implemented so far

CEMC

BEMC

SOLENOID

FEMC

Update on track resolution studies


Tracking elements

2x7 disks with up to 280 mm radius; MAPS pixels assumed N sectors per disk; 200 m silicon-equivalent thickness digitization: same as for vertex tracker

forward/backward silicon trackers:

TPC:

GEM trackers:

~2m long; gas volume radius [300..800] mm 1.2% X0 IFC, 4.0% X0 OFC; 15.0% X0 aluminum

endcaps digitization: idealized, assume 1x5 mm GEM pads

3 disks behind the TPC endcap; STAR FGT design digitization: 100 m resolution in X&Y; gaussian

smearing

vertex silicon tracker: 6 MAPS layers at up to of 160mm radius; STAR ladder design digitization: discrete ~20x20 m2 pixels


Tracker view (June’2013)

BGT

BST

FST

VST

TPC

FGT

06/20/2013

Tracking scheme So-called ideal PandaRoot track “finding”:

PandaRoot track fitting code:

Monte-Carlo hits are digitized on a per-track basis

Effectively NO track finder

Kalman filter Steering in magnetic field Precise on-the-fly accounting of material

effects

A.Kiselev

MRS-B1 solenoiddesign used


Example plots from tracking code

1 GeV/ctracks at

32 GeV/ctracks at

<ndf> = 206

<ndf> = 9

-> look very reasonable from statistical point of view


Momentum resolution plot#1track momentum resolution vs. pseudo-rapidity

-> expect 2% or better momentum resolution in the whole kinematic range


Momentum resolution plot#2track momentum resolution at vs. Silicon

thickness

-> ~flat over inspected momentum range because of very small Si pixel size


Momentum resolution plot#3track momentum resolution at vs. Silicon

pixel size

-> 20 micron pixel size is essential to maintain good momentum resolution


Tracker “designer” tools Allow to easily add “simple” tracking

detector templates to the “official” geometry Require next to zero coding effort

-> see tutorials/designer/tracking directory for details

Which momentum resolution for 10 GeV/c pions will I get with 10 MAPS layers at


Tracker “designer” tools

Create geometry file (few dozens of lines ROOT C script)

Include few lines in “standard” sim/digi/reco scripts:

Analyze output ROOT file

-> workflow sequence:

Calorimeters in EicRoot


General Code written from scratch Unified interface (geometry definition,

digitization, clustering) for all EIC calorimeter types

Rather detailed digitization implemented: configurable light yield

exponential decay time; light collection in a time window

attenuation length; possible light reflection on one “cell” end

SiPM dark counting rate; APD gain, ENF, ENC configurable thresholds


Backward EM Calorimeter (BEMC)

PWO-II, layout a la CMS & PANDA

-2500mm from the IP both projective and non-

projective geometry implemented

digitization based on PANDA R&D

10 GeV/c electron hitting one of the four BEMC quadrants Same event (details of shower development)


BEMC energy resolution plot#1

-> projective geometry may lag behind in terms of resolution?

electrons at


BEMC energy resolution plot#2

“Realistic” digitization: light yield 17pe/MeV; APD gain 50, ENF 2.0, ENC 4.2k; 10 MeV single cell threshold;

non-projective geometry;

-> would be interesting to check sensitivity to all settings in detail


Forward EM Calorimeter (FEMC)

tungsten powder scintillating fiber sampling calorimeter technology

+2500mm from the IP; non-projective geometry sampling fraction for e/m showers ~2.6% “medium speed” simulation (up to energy deposit in fiber

cores) reasonably detailed digitization; “ideal” clustering code

tower (and fiber) geometrydescribed precisely


FEMC energy resolution study

-> good agreement with original MC studies and measured data

“Realistic” digitization: 40MHz SiPM noise in 50ns gate; 4m attenuation length; 5 pixel single tower threshold; 70% light reflection on upstream fiber end;

3 degree track-to-tower-axis incident angle


FEMC tower “optimization”

original mesh

optimized mesh -> optimized mesh design can probably decrease “constant term” in energy resolution


Barrel EM Calorimeter (CEMC)

same tungsten powder + fibers technology as FEMC, … … but towers are tapered non-projective; radial distance from beam line [815 ..

980]mm

-> barrel calorimeter collects less light, but response (at a fixed 3o angle) is perfectly linear


CEMC energy resolution plot#1

-> simulation does not show any noticeable difference in energy resolution between straight and tapered tower calorimeters

3 degree track-to-tower-axis incident angle



-> energy response goes down with polar angle because of effectively decreasing sampling fraction; quite reasonable

8 GeV/c electrons



-> energy resolution degrades with polar angle because of effectively decreasing sampling frequency (?)

8 GeV/c electrons


Calorimeter “designer” tools Allow to easily add “simple” calorimeter

detector templates to the “official” geometry Require next to zero coding effort

Which energy resolution for 1 GeV/c electrons will I get with a “basic” PWO calorimeter


Calorimeter “designer” tools As long as the following is true:

… one can with a moderate effort (99% of which is writing a ROOT C macro with geometry and mapping description) build custom EicRoot-friendly calorimeter which can be used for both standalone resolution studies and/or as an optional EIC device (and internal cell structure does not matter)

-> see tutorials/designer/calorimetry directory for details

your dream calorimeter is a logical 2D matrix … … composed of “long cells” as elementary units, all the game is based on (known) light output per energy

deposit, energy resolution after “ideal” digitization suffices as a

result

Documents

A. Kiselev BNL, 06/20/2013